Electronic devices such as smartphones can emit radiation, for example, radiofrequency (RF) radiation via a cellular signal transmitted by an antenna of the smartphone. Additionally, smartphones can also receive cellular signals as a form of radiation. Other types of wireless signals (e.g., WiFi signals based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards) can also be transmitted and received.
Often, users might want to block signals being emitted from the smartphone or received by the smartphone. For example, some users might want to reduce the amount of radiation that their body might absorb from the smartphone. Some users might also want to prevent a smartphone from receiving a signal to maintain a higher level of privacy.